The invention relates to a guide segment fitted with rollers on a continuous casting installation, whereby at least some rollers each comprise at least two aligned roller bodies mounted with end roller pivots in inner and outer bearings, whereby the inner bearings are designed as movable bearings in the form of cageless heavy-duty bearings and the outer bearings are designed as fixed bearings.
Guide segments fitted with rollers on continuous casting installations serve to transfer the band-shaped cord emerging from the casting die with still liquid core through an arc from the vertical into the horizontal. The mechanical load on the roller seating thereby arising is great, above all on the outer arc of the guide. It is customary, therefore, not to fit the guide-segments with one-piece rollers extending over the whole cord width, but rather with multi-piece rollers, especially with two aligned roller bodies. Since on the one hand the rollers have to be mounted so as to be axially fixed, and on the other hand fixed bearings, which perform this task, withstand a lower mechanical load than cageless heavy-duty bearings obtainable only in the form of movable bearings, such as for example CARB bearings from the firm SKF, the fitting of guide segments with rollers has in recent times undergone a switch to the use of two aligned roller bodies per roller in each case, the outer bearings of which are designed as fixed bearings and the inner bearings of which are designed as movable bearings in the form of cageless CARB bearings. With the design of the inner bearings as special movable bearings, the higher loading of the roller by the cord in the area of the cord centre is taken into account.
In the areas of the arc-shaped guide subject to particularly great mechanical stress, especially at the outer arc, two aligned roller bodies per roller are not sufficient as a support for the cord, especially in the case of relatively wide cords. For this reason, three roller bodies per roller aligned with one another have in the past been used in these areas. However, since the cageless heavy-duty bearings capable of greater mechanical loads withstand only a limited axial relative displacement of their ball races and therefore, with two roller bodies arranged aligned, each roller body is fixed axially at one end with a fixed bearing, the application of the bearing principle xe2x80x9cone fixed and one movable bearing per roller bodyxe2x80x9d for the middle roller body would not lead, on account of the lower loading capacity of the fixed bearing, to the desired successful outcome of an overall higher loading capacity of the roller.
The problem underlying the invention is to provide a guide segment fitted with rollers on a continuous casting installation, said guide segment being capable of withstanding higher mechanical loads than a guide segment with two roller bodies per roller in each case.
According to the invention, this problem is solved with a guide segment of the kind mentioned at the outset by the fact that, between the two roller bodies and aligned therewith, a further roller body is mounted axially floating with its two end roller pivots in movable bearings in the form of cageless heavy-duty bearings, whereby the free axial mobility of the middle roller body is limited by stops acting between the inner roller pivots of the outer roller bodies and the two roller pivots of the middle roller body.
In the case of the guide segment according to the invention, the higher loading capacity of the at least three-piece roller is achieved by the fact that, in the central support area of the cord, where the roller must apply the greatest supporting force, only the cageless movable bearings capable of withstanding high loads are used. The so-called CARB bearings from the firm SKF, which are available on the market, currently come into consideration for this. It is conceivable, however, for other movable bearings comparable in loading capacity to be used. The limited permissible axial mobility for these movable bearings is limited solely by the outer fixed bearings of the outer roller bodies. In the case of the outer roller bodies this takes place directly via their outer fixed bearings and in the case of the middle roller body via the stops on the axially fixed outer roller bodies.
As known per se, the fixed bearings are preferably self-aligning roller bearings.
The axial mobility of the middle roller body can be limited in terms of construction by the fact that the two inner roller pivots of the outer roller bodies and/or the roller pivots of the middle roller body have on their end faces butting discs which limit the axial play of the middle roller body in such a way that, in the cold state of the roller bodies, it is xe2x89xa6 the permitted axial mobility of the movable bearings of the middle roller body and  greater than  than the sum of the maximum axial heat expansion of the roller bodies.
In order to have the rollers mounted in the optimum fashion at operating temperature, provision is made according to a development of the invention such that the bearing rings of the movable bearings of the outer roller bodies are axially offset with respect to one another in their cold state in such a way that they are in their optimum bearing position in the operational hot state.